Gas chromatography-mass spectrometry using microvial insert thermal desorption for the determination of BTEX in edible oils

Abstract

Microvial insert thermal desorption is evaluated as a sample introduction system for gas chromatography-mass spectrometry (GC-MS) determination of benzene, toluene, ethylbenzene and xylene isomers (BTEX) in vegetable oil samples. Under the optimized conditions, the BTEX contained in a 50 μL oil sample placed in the microvial insert were thermally vaporized at 140 °C for 5 min while helium at a flow of 120 mL min⁻¹ and pressure of 4.3 psi propelled the analytes to the programmable temperature vaporizator (PTV), where they were focused at 15 °C. The compounds were finally injected into the GC column by rapidly heating the PTV at 270 °C. The proposed method provided good linearity between 10 and 200 μg L⁻¹. High sensitivity, with detection limits in the 0.7–1.2 μg L⁻¹ range, depending on the compound, was achieved with a low sample volume and minimum sample handling. Fourteen edible vegetable oil samples were analyzed and the analytes were found in a wide concentration range.